Randy used to have poor health. recently, he has lost a lot of weight and has started feeling much better, but he doesn't know which of his life changes contributed to the improvement. which change most likely randy get better health?

a he won most of the arguments with his friends.
b he located a new organic food store nearby.
c he found a new frozen yogurt store he likes.
d he started getting a full night of restful sleep.

Investigator a has biological specimens that are coded and linked to identifiers of the source individuals. investigator a provides the specimens to investigator b but does not provide the individual identifiers. investigator b agrees not to re-identify the source individuals. is investigator b's research using the biospecimens human subjects research according to the definition of human subjects research in the federal regulations?